How large is a 1.8 pound yellow perch? Well, it is 1.8 pounds...

OK, all joking aside, anywhere from a thin 16" to a very plump 12" or so.
Yellow perch spawn very early in the year, usually not much later than shortly after ice out when water temps are in the upper 30's to low 40's. However spawning can sometimes be drug out later into spring.
The LMB in your area will probably spawn sometime in later May to early June, when water temps reach 65-68 degrees or so.
The BC will spawn in approximately late April, in water temps of about the upper 50's.
The BG will most likely start spawning in mid May and will continue to sporadically spawn through August.
As far as how big will all those species get with another year or two of added growth with good forage... So many variables, its hard to say!